Memory management - JavaScript | MDN

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WeakMaps and WeakSets

WeakMap and WeakSet are data structures whose APIs closely mirror their non-weak counterparts: Map and Set. WeakMap allows you to maintain a collection of key-value pairs, while WeakSet allows you to maintain a collectio

WeakMaps and WeakSets

WeakMap and WeakSet are data structures whose APIs closely mirror their non-weak counterparts: Map and Set. WeakMap allows you to maintain a collection of key-value pairs, while WeakSet allows you to maintain a collectio

WeakMaps and WeakSets

WeakMap and WeakSet are data structures whose APIs closely mirror their non-weak counterparts: Map and Set. WeakMap allows you to maintain a collection of key-value pairs, while WeakSet allows you to maintain a collectio

WeakMaps and WeakSets

WeakMap and WeakSet are data structures whose APIs closely mirror their non-weak counterparts: Map and Set. WeakMap allows you to maintain a collection of key-value pairs, while WeakSet allows you to maintain a collectio

Registered symbols

WeakMaps and WeakSets

WeakMap and WeakSet are data structures whose APIs closely mirror their non-weak counterparts: Map and Set. WeakMap allows you to maintain a collection of key-value pairs, while WeakSet allows you to maintain a collectio

Avoid using them where possible

Note: WeakRef and FinalizationRegistry offer direct introspection into the garbage collection machinery. Avoid using them where possible because the runtime semantics are almost completely unguaranteed.

FinalizationRegistry

Note: WeakRef and FinalizationRegistry offer direct introspection into the garbage collection machinery. Avoid using them where possible because the runtime semantics are almost completely unguaranteed.

WeakRefs and FinalizationRegistry

Note: WeakRef and FinalizationRegistry offer direct introspection into the garbage collection machinery. Avoid using them where possible because the runtime semantics are almost completely unguaranteed.

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This page was last modified on Apr 6, 2026 by MDN contributors.

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